Tuesday, March 17, 2009

Quick-Release Fasteners

It's Diane, and having talked last time about vibration-proof fasteners, I thought I'd tackle the opposite concept: quick-release fasteners. Because here's the thing: Sometimes you want your fastener to hold, and sometimes you want it "easily persuaded to let go."

This presents a new design challenge for components, and that is to make them quickly and easily movable or removable, without sacrificing some worthwhile fastening properties. The examples I'm sharing with you today use various techniques to achieve this.

Let's start with the very simple GN 6303.1 knurled nuts. These are used in applications where the nut has to be completely removed after the releasing operation and refitted very rapidly for re-clamping. It's based on the DIN 6303 knurled nut, with the modification you see in this line drawing. To mount the knurled quick release nut, you tilt it over the threaded spindle, slide it down the spindle to its final position, then align the nut with the threaded spindle by straightening it from the tilted position. This meshes the two components. Only a fraction of a rotation is needed to achieve clamping.

A similar principle is employed in the design of several of our hand knobs. The GN 6336.3 is a nylon plastic hand knob with a steel hub, used in applications where the knob has to be completely removed and refitted very rapidly for re-clamping.

Our LMAQ knob is an all-plastic alternative, made of thermoplastic in a nice modern design with good shock-resistance.

Quick-release capabilities can also be achieved using other techniques in the design of the part. For example, our GN 6333 quick-release hex nuts are manufactured so there is no "locking" of the thread. Unlike the items previously discussed, these nuts slide down the spindle without tilting the nut. Once in the final position for clamping, the upper hex part of the nut is pressed down over the split nut so that it locks the threads to the threaded spindle. Then the nut can be tightened by using a wrench, securing it into its locked position. The nut can then be removed by depressing pins on the sides of the nut that release it from its locked position, allowing the nut to be quickly removed by sliding it up from the threaded spindle.

For another type of quick-release technology, check out our GN 124 quick-release pins. The balls in these pins are spring loaded, but not rigidly, so they have a relatively low axial holding strength. The illustration shows the type of application where this kind of pin can be used, allowing for quick fixing and removal.

You know, although many of the components we sell at J.W. Winco seem simple and basic, it never ceases to amaze me how significant are the subtleties of their design. This is why our Technical Sales Associates are so well versed in how to find the appropriate part to fit a customers' application.